It is desirable to provide a well drilling apparatus for drilling oil and gas wells or the like, in which the component parts can be assembled at substantially ground level and then raised to a high elevation where they are operational and in which all of the raising operations can be accomplished with power supplied by the drawworks. Several such apparatus have been proposed in the prior art. Woolslayer et al (U.S. Pat. No. 3,228,151), for example, teach a complicated oil drilling apparatus in which either the rotary table is carried by the mast, or in which the mast has short rear legs and front legs pivoted to the base. A single elevator platform is utilized to carry the drawworks to its operational position. Branham et al (U.S. Pat. No. 3,749,183) teach a mast structure which is pivotally mounted on a base and which includes a single elevator platform for carrying the drawworks to its operational position. The Branham et al structure further requires a separate pivotal pipe rack which is separately mounted on the base and pivoted into position and a rotary table platform which must be lifted to platform level and connected between the elevated drawworks platform and pipe rack. Donnally (U.S. Pat. No. 3,803,780) teaches a particular form of collapsible ginpole to which a mast structure is pivotally mounted. The Donnally structure has a single elevator platform for raising the drawworks and requires assembly of a working floor support and working floor after the mast structure has been lifted into position and the ginpole collapsed. Jenkins et al (U.S. Pat. No. 3,807,109) teach a ginpole carried by an elevator drawworks platform. The mast structure is pivotally mounted on a reclining setback support member, which, in turn, is pivotally mounted on the base. None of the above show or suggest a mast structure pivotally mounted on an elevator platform.
Dreco, Inc. manufactures a self-elevating "Slingshot" structure which raises from ground level to drilling position utilizing hydraulically driven winches (separate from the drawworks) mounted in each base assembly. The Dreco structure includes a single elevator platform carrying the mast structure, rotary table, drawworks and setback area. In addition to requiring separate winches (making the structure extremely expensive), the Dreco single elevator platform structure has proven extremely difficult in field use; the single platform cannot be lowered without interfering with certain control valve structures (such as the control valve structures commonly referred to as "Christmas trees") required to be placed on wellheads to control gas pressures and the like while the platform is still in its elevated position.
It is therefore an object of the present invention to provide an improved oil and gas drilling apparatus.
Another object of the invention is to provide an improved drilling apparatus wherein the drawworks and mast can be assembled onto the base structure at ground level and then raised to an elevated operating position.
Yet another object of the invention is to provide a simplified drilling apparatus, the component parts being assemblable at ground level and then raisable to a high operational elevation, in which all of the raising operations can easily be accomplished with power supplied by the drawworks.
Still another object of the invention is to provide a well drilling apparatus in which the drawworks and mast structure can be lowered by elevator or platform means without interfering with any control valve structures placed on the wellhead while the well drilling apparatus is in its raised operational position.
These and other objects are accomplished in accordance with the present invention in which a first swing-up elevator platform on which the mast structure is pivotally mounted is provided for elevating the mast structure to a high operational level after the mast structure has been raised to its erect position; and, a second swing-up elevator platform is provided to carry the drawworks to the same high level at which the two elevator platforms are coupled together to form the working floor. All of the raising and elevating operations can be accomplished with power supplied by the drawworks. The elevator platforms may be lowered after the drilling operation has been accomplished without interfering with any control valve structures that have been placed on the wellhead while the structure was at its raised operational level, because the swing-up elevator platforms swing down in opposite directions over any such valve structure.
In one embodiment of the invention, a drawworks swing-up elevator platform is mounted on a base structure and a mast-setback swing-up elevator platform is also mounted on the base structure. The elevators swing up from either end of the base and meet near the center of the base. The front legs of a mast are pivotally mounted on the mast-setback elevator platform along with a mast ginpole. The rotary table is mounted in the mast-setback elevator platform and forms part of the mast-setback elevator. A second elevator or ginpole is mounted on the base structure. The mast structure is raised to an erect or vertical position, utilizing the mast ginpole and drawworks. The mast ginpole provides the rear legs of the mast structure once the mast structure has been raised to the vertical position. The drawworks is then utilized in conjunction with the elevator ginpole to raise the mast-setback elevator platform up to its elevated operational position and the mast-setback elevator platform is coupled to the elevator ginpole. The drawworks then utilizes the elevator ginpole to raise the drawworks elevator platform up to the same elevated level as the mast-setback elevator where the front end of the drawworks elevator platform meets the rear end of the mast-setback elevator platform. The drawworks elevator platform is then coupled to the mast-setback elevator, or alternatively, to the elevator ginpole to lock it into operational position. The mast-setback elevator platform is sufficiently large to provide the working floor and includes the setback area of the drilling apparatus.